Sexual network structure among a household sample of urban african american adolescents in an endemic sexually transmitted infection setting

Investigating the Relative Influence of Romantic Sex Partners and Close Friends on Adolescent Alcohol and Marijuana Use

A large body of research has identified peer exposure as a key factor driving adolescent substance use. However, findings on the role of sex partners are less robust and mixed. This study aims to fill this gap by examining the independent contribution of close friends' and sex partners' alcohol and marijuana use on adolescents' use of these substances. A secondary data analysis of social network data collected in 2000-2002 from a household sample of African American youth (14-19 years old) in the Bayview and Hunter's Point neighborhoods of San Francisco was conducted. Index participants and their nominated close friends and romantic sex partners (N = 104 triads) self-reported recent alcohol and marijuana use (defined as any use in the past 3 months). Generalized estimated equations were used to estimate the independent association between adolescent's recent substance use and their friend's and sex partner's use. Adolescents with a marijuana-using romantic sex partner had a nearly six-fold higher odds of using marijuana compared to adolescents with a non-using partner, controlling for close friend's marijuana use and other confounders [OR:5.69, 95%CI: 1.94, 16.7]; no association with close friend's marijuana use was found. A similar pattern was observed for alcohol use. Adolescents with an alcohol-using romantic sex partner had increased odds of using alcohol compared to adolescents with a non-using partner, controlling for close friend's alcohol use and other confounders [OR:2.40, 95%CI: 1.02, 5.63]; no association with close friend's alcohol use was found. Romantic sex partners may play a unique and significant role in adolescent substance use. Peer-focused interventions may be more effective if they consider romantic sex partners. Future research should consider the role of romantic sex partners in changing social context related to substance use from adolescence to young adulthood.

Love moderates the relationship between partner type and condom use among women engaging in transactional vaginal sex

Background Relationship characteristics and day-to-day variation in affective state have been associated with HIV risk behaviour. However, no research has assessed the impact of these factors on event-level condom use among women engaging in transactional sex.

METHODS

Twenty-six women engaging in transactional sex were enrolled in a prospective study of their sexual health. They completed diaries about multi-level predictors of condom use during vaginal sex twice, daily.

RESULTS

Over 4 weeks, 18 participants reported 87 paid/traded vaginal intercourse events. Of these, 51.7% were condom protected. The majority of paid/traded events (81.5%) occurred with a non-romantic partner. After controlling for partner type, feeling in love on a given day was associated with higher odds of condom use during paid/traded sexual events, while having sex on the weekend and at night were associated with lower odds of condom use (all P≤0.05). There was a significant interaction between being in love and using condoms during transactional sex (P<0.01). In paid/traded sexual events with romantic partners, the frequency of condom use was 71.4% (5/7) when women did not report love and 40% (4/10) when love was reported. In sexual events with non-romantic partners, the frequency of condom use was 43.8% (14/32) when women did not report love and 59.5% (22/37) when love was reported.

CONCLUSIONS

Women were less likely to report protected sex with romantic partners and more likely to report protected sex with non-romantic partners when they are in love. Interventions focusing on the link between day-to-day variation in affective state on condom use may help women with risk management across partner types.

Can Social Network Analysis Help Address the High Rates of Bacterial Sexually Transmitted Infections in Saskatchewan?

BACKGROUND

Saskatchewan has one of the highest rates of gonorrhea among the Canadian provinces-more than double the national rate. In light of these high rates, and the growing threat of untreatable infections, improved understanding of gonorrhea transmission dynamics in the province and evaluation of the current system and tools for disease control are important.

METHODS

We extracted data from a cross-sectional sample of laboratory-confirmed gonorrhea cases between 2003 and 2012 from the notifiable disease files of the Regina Qu'Appelle Health Region. The database was stratified by calendar year, and social network analysis combined with statistical modeling was used to identify associations between measures of connection within the network and the odds of repeat gonorrhea and risk of coinfection with chlamydia at the time of diagnosis.

RESULTS

Networks were highly fragmented. Younger age and component size were positively associated with being coinfected with chlamydia. Being coinfected, reporting sex trade involvement, and component size were all positively associated with repeat infection.

CONCLUSIONS

This is the first study to apply social network analysis to gonorrhea transmission in Saskatchewan and contributes important information about the relationship of network connections to gonorrhea/chlamydia coinfection and repeat gonorrhea. This study also suggests several areas for change of systems-related factors that could greatly increase understanding of social networks and enhance the potential for bacterial sexually transmitted infection control in Saskatchewan.

Reducing Missed Opportunities: Pairing Sexually Transmitted Infection Screening With Syringe Exchange Services

About 17.5% of sexually active injection drug users recruited from a syringe exchange in Camden, NJ (n = 120) screened positive for chlamydia/gonorrhea. Among these cases, 40% were detected via extragenital screening. This pilot demonstrates that colocating sexually transmitted infection control with syringe exchange leads to sexually transmitted infection case finding.

Amino acid positions subject to multiple coevolutionary constraints can be robustly identified by their eigenvector network centrality scores

As proteins evolve, amino acid positions key to protein structure or function are subject to mutational constraints. These positions can be detected by analyzing sequence families for amino acid conservation or for coevolution between pairs of positions. Coevolutionary scores are usually rank-ordered and thresholded to reveal the top pairwise scores, but they also can be treated as weighted networks. Here, we used network analyses to bypass a major complication of coevolution studies: For a given sequence alignment, alternative algorithms usually identify different, top pairwise scores. We reconciled results from five commonly-used, mathematically divergent algorithms (ELSC, McBASC, OMES, SCA, and ZNMI), using the LacI/GalR and 1,6-bisphosphate aldolase protein families as models. Calculations used unthresholded coevolution scores from which column-specific properties such as sequence entropy and random noise were subtracted; "central" positions were identified by calculating various network centrality scores. When compared among algorithms, network centrality methods, particularly eigenvector centrality, showed markedly better agreement than comparisons of the top pairwise scores. Positions with large centrality scores occurred at key structural locations and/or were functionally sensitive to mutations. Further, the top central positions often differed from those with top pairwise coevolution scores: instead of a few strong scores, central positions often had multiple, moderate scores. We conclude that eigenvector centrality calculations reveal a robust evolutionary pattern of constraints-detectable by divergent algorithms--that occur at key protein locations. Finally, we discuss the fact that multiple patterns coexist in evolutionary data that, together, give rise to emergent protein functions.

Social network recruitment for Yo Puedo: an innovative sexual health intervention in an underserved urban neighborhood—sample and design implications

Most existing evidence-based sexual health interventions focus on individual-level behavior, even though there is substantial evidence that highlights the influential role of social environments in shaping adolescents' behaviors and reproductive health outcomes. We developed Yo Puedo, a combined conditional cash transfer and life skills intervention for youth to promote educational attainment, job training, and reproductive health wellness that we then evaluated for feasibility among 162 youth aged 16-21 years in a predominantly Latino community in San Francisco, CA. The intervention targeted youth's social networks and involved recruitment and randomization of small social network clusters. In this paper we describe the design of the feasibility study and report participants' baseline characteristics. Furthermore, we examined the sample and design implications of recruiting social network clusters as the unit of randomization. Baseline data provide evidence that we successfully enrolled high risk youth using a social network recruitment approach in community and school-based settings. Nearly all participants (95%) were high risk for adverse educational and reproductive health outcomes based on multiple measures of low socioeconomic status (81%) and/or reported high risk behaviors (e.g., gang affiliation, past pregnancy, recent unprotected sex, frequent substance use; 62%). We achieved variability in the study sample through heterogeneity in recruitment of the index participants, whereas the individuals within the small social networks of close friends demonstrated substantial homogeneity across sociodemographic and risk profile characteristics. Social networks recruitment was feasible and yielded a sample of high risk youth willing to enroll in a randomized study to evaluate a novel sexual health intervention.

The association between social networks and self-rated risk of HIV infection among secondary school students in Moshi Municipality, Tanzania

This study describes the social networks of secondary school students in Moshi Municipality, and their association with self-rated risk of human immunodeficiency virus (HIV) infection. A cross-sectional analytical study was conducted among 300 students aged 15–24 years in 5 secondary schools in Moshi, Tanzania. Bonding networks were defined as social groupings of students participating in activities within the school, while bridging networks were groups that included students participating in social groupings from outside of the school environs. A structured questionnaire was used to ask about participation in bonding and bridging social networks and self-rated HIV risk behavior. More participants participated in bonding networks (72%) than in bridging networks (29%). Participation in bridging networks was greater among females (25%) than males (12%, p < .005). Of 300 participants, 88 (29%) were sexually experienced, and of these 62 (70%) considered themselves to be at low risk of HIV infection. Factors associated with self-rated risk of HIV included: type of school (p < .003), family structure (p < .008), being sexually experienced (p < .004), having had sex in the past three months (p < .009), having an extra sexual partner (p < .054) and non-condom use in last sexual intercourse (p < .001), but not the presence or type of social capital. The study found no association between bonding and bridging social networks on self-rated risk of HIV among study participants. However, sexually experienced participants rated themselves at low risk of HIV infection despite practicing unsafe sex. Efforts to raise adolescents’ self-awareness of risk of HIV infection through life skills education and HIV/acquired immunodeficiency syndrome risk reduction strategies may be beneficial to students in this at-risk group.

Cohort Profile: The Likoma Network Study (LNS)

The Likoma network study (LNS) investigates the sexual networks connecting the inhabitants of Likoma, a small island of Lake Malawi with high HIV prevalence. Whereas previous studies of sexual networks and HIV/AIDS in sub-Saharan countries have focused solely on the personal networks of a small number of respondents, the LNS attempts to document the sexual networks of the entire adult population of Likoma. To do so, it uses a unique sociocentric study design, in which all members of the local population are contacted for a survey interview and are asked to nominate their five most recent sexual partners. Using these data, quasi-complete 'maps' of the sexual networks connecting inhabitants of the island can be constructed. These maps allow investigation of the impact of networks on HIV epidemiology and can inform mathematical models of HIV prevention. In addition to data on sexual networks, the LNS data include information on the social networks (e.g. friendship), socioeconomic characteristics and HIV status of Likoma's residents. Baseline data were collected in 2005-06. A first follow-up was conducted in 2007-08 and a second follow-up is planned for early 2013. Access to the LNS data is contingent upon review of a short concept paper and forming collaborations with LNS investigators.

Spread of methicillin-resistant Staphylococcus aureus in a large tertiary NICU: network analysis

OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) colonization in NICUs increases the risk of nosocomial infection. Network analysis provides tools to examine the interactions among patients and staff members that put patients at risk of colonization.

METHODS

Data from MRSA surveillance cultures were combined with patient room locations, nursing assignments, and sibship information to create patient- and unit-based networks. Multivariate models were constructed to quantify the risk of incident MRSA colonization as a function of exposure to MRSA-colonized infants in these networks.

RESULTS

A MRSA-negative infant in the NICU simultaneously with a MRSA-positive infant had higher odds of becoming colonized when the colonized infant was a sibling, compared with an unrelated patient (odds ratio: 8.8 [95% confidence interval [CI]: 5.3-14.8]). Although knowing that a patient was MRSA-positive and was placed on contact precautions reduced the overall odds of another patient becoming colonized by 35% (95% CI: 20%-47%), having a nurse in common with that patient still increased the odds of colonization by 43% (95% CI: 14%-80%). Normalized group degree centrality, a unitwide network measure of connectedness between colonized and uncolonized patients, was a significant predictor of incident MRSA cases (odds ratio: 18.1 [95% CI: 3.6-90.0]).

CONCLUSIONS

Despite current infection-control strategies, patients remain at significant risk of MRSA colonization from MRSA-positive siblings and from other patients with whom they share nursing care. Strategies that minimize the frequency of staff members caring for both colonized and uncolonized infants may be beneficial in reducing the spread of MRSA colonization.

Longitudinal associations among relationship factors, partner change, and sexually transmitted infection acquisition in adolescent women

OBJECTIVES

New sex partners put adolescents at increased risk for sexually transmitted infections (STIs), even when these sex partners are nonoverlapping. Although the risk of partner change is well described, little is known about its antecedents. We prospectively examined associations between relationship characteristics, partner change, and subsequent STI during intervals of "serial monogamy."

METHODS

As part of a longitudinal study, 332 adolescent women were interviewed and tested for gonorrhea, chlamydia, and trichomonas every 3 months for up to just over 6 years. Interviews covered partner-specific relationship characteristics and sexual behaviors. The quarterly interval, a 3-month period bracketed by interviews and STI testing, was the unit of analysis. We examined associations among relationship factors, partner change, and subsequent STI using a series of mixed regression models, controlling for age, STI at Time 1, and condom nonuse.

RESULTS

Age, lower relationship quality, and lower levels of partner closeness to friends and family predicted partner change from Time 1 to Time 2. In turn, partner change was associated with acquisition of a new STI at Time 2. Although relationship factors did not exert a direct effect on STI at Time 2, they improved partner change-STI model fit. Similar patterns were seen with each organism.

CONCLUSION

Relationship factors drive partner change, which in turn contributes to STI acquisition. STI prevention research may need to focus on the relationship antecedents to partner change, in addition to the partner change itself.

The available pool of sex partners and risk for a current bacterial sexually transmitted infection

PURPOSE

Sexually transmitted infection (STI) transmission models propose that incident STIs are related to exposure to infected sex partners. The objective of this study was to determine whether the prevalence of STIs among the available pool of sex partners in a neighborhood, measured indirectly, is an independent determinant of a current incident STI.

METHODS

The target population comprised 58,299 English-speaking, sexually active 15- to 24-year-olds in 486 census block groups (CBGs) in Baltimore, MD. A sample of 65 CBGs was selected using a stratified, systematic, probability-proportional-to-size strategy and 13,873 households were randomly selected. From 2004 through 2007, research assistants administered an audio computer-assisted interview survey and collected biologic samples for gonorrhea and chlamydia testing.

RESULTS

The final sample size included 575 participants from 63 CBGs. Additional data provided gonorrhea prevalence from 2004 through 2005 per 15- to 49-year-old persons per 100,000 per CBG. After adjustment for individual-level STI risk factors in a multilevel probability model, adolescents and young adults living in high (vs. low) prevalence STI areas were 4.73 times (95% confidence interval [CI]: 3.65-6.15) more likely to have a current incident STI.

CONCLUSIONS

To inform prevention programs, future research should focus on identifying mechanisms through which context causes changes in local sexual networks and their STI prevalence.